1. Field
Apparatuses consistent with exemplary embodiments relate to stacked image sensors including a photoelectric conversion region for measuring an image and a photoelectric conversion region for auto focusing, which are vertically stacked.
2. Description of the Related Art
An auto-focusing (AF) method used by a camera includes phase detection AF and contrast detection AF. In the phase detection AF, images are measured by dividing light that enters through a focusing lens into more than two AF sensors. At this point, a focusing distance is determined at a location of the focusing lens when locations of the images measured by the AF sensors are almost equal.
In the contrast detection AF, a location of a focusing lens where a contrast difference between adjacent images is the largest is determined as a focusing distance. The contrast detection AF is advantageous over the phase detection AF in that a focus is correctly determined, but the determining speed is slower than in the phase detection AF.
A method of determining a focusing distance that is recently generally used is a hybrid AF method. In the hybrid AF method, some regions of image sensors are replaced by AF sensors, and the phase detection AF is used to the vicinity of a focus when an AF function is executed, and afterwards, the contrast detection AF is used to finely adjust the correct focus.
However, since some of the image sensors have been replaced by AF sensors, image information may be reduced in proportion to the number of replaced AF sensors, and thus, the resolution of a camera may be reduced.